Nowadays, people can get the same TV content from different vendors through different communication channels, such as satellite, cable, phone line, and Internet. The choice of communication channels often has many geographic and demographic considerations. For example, satellite receivers may be the most commonly used devices for households in the rural areas to receive TV signals. But it is probably more common for households in big metropolitan areas to use cable connections or over the air (OTA) antennas to receive TV signals. Although many people still watch TV programs on TVs, younger viewers may increasingly choose to watch TV programs on a computer that is coupled to the Internet, or even a smartphone supporting 3G/4G wireless communications. The existence of diversified communication channels for receiving TV programs is that it is more challenging to provide an efficient, accurate estimate of the viewership rating for a particular TV program at a large population level (e.g., at a national level).